Children are exposed to persistent organic pollutants (POPs) during fetal life and breast-feeding. In a case-control study including cases of childhood cancer reported to the Cancer Registry 1988–1991 (n=962) we used breastfeeding duration as a surrogate for exposure to POPs. One matched control per case was used. Information on breast-feeding, vaccinations and chronic illness was collected from copies of the children’s Child Health Center records.

Overall, breast-feeding did not affect the risk of childhood cancer, OR=1.0 (95% CI=0.7–1.3) using breast-feeding up to one month as reference. For non-Hodgkin lymphoma (NHL) OR for breast-feeding for >1 month yielded OR=5.0 (95% CI=1.1–23).

No association was seen between preschool vaccinations and childhood cancer except for lymphomas and measles/measles-mumps-rubella vaccination, OR=0.2 (95% CI=0.1–0.6). Increased risk of all cancer was found for congenital malformations, OR=1.7 (95% CI=0.97–2.9), especially of leukemia, OR=3.0 (95% CI=1.5–5.8). Children with disorders of brain function had an increased risk of all cancer, OR=6.0 (95% CI=1.3–27), especially of brain tumors, OR=10 (95% CI=1.3–78).

A childhood population expected to be more exposed to POPs is children of fishermen. In a register-based study, the cancer incidence rates in a cohort of fishermen children (at age 0-19 years) were compared to the rates of referent children. A modestly increased incidence rate ratio (IRR) of childhood cancer was found, IRR=1.38 (95% CI=0.96–2.00) and an increased IRR for acute lymphoid leukemia, IRR=2.65 (95% CI=1.005–6.97). In west coast fishermen children, an increased IRR was observed for NHL, IRR=3.19 (95% CI=0.98–10.4).